Ggordge,
The map assigned to the SU material can be used for one map type in the Maxwell settings. The first option in the maps-set maps dialog “SketchUp Map type” defines for witch type you want to use it, so selecting Bumping there uses the SU map as bump map. The other map types have to be assigned separately by maps- pick XXX map and selecting a file.
(The thing that was confusing me was when I first selected a diffuse map and then changed the SU map type to bump I “lost” the diffuse map from the rendering and it has to be re-assigned… You can’t see what map is assigned afterwards).
To avoid confusion I suggest the maps UI should be changed to something like this:

Not Available indicates this map type can not be used with the selected Maxwell material type.
… Actually it would make sense to move the whole map thing to material settings, like it is in the other plug-ins, so you could have only the map types available for the specific material type visible.
Add a similar possibility to use SketchUp colours or specify a new one and you can now set all Maxwell settings independently of SU. Add a possibility to save the Maxwell settings in a separate library, (and to get them from the library), and we can have some kind of materials library after all. (This is still not optimal as using two separate materials & libraries simultaneously can be confusing, but I think it would be an acceptable workaround). You could change “Check Material Type” to “Edit Material” witch would open the material settings for that specific material, without the need for the user to know what type has been set for it.
If we can go one step further there could be a Ruby script that checks the SU materials used in the model and automatically connects them to Maxwell materials by matching names.
The “standalone MXS editor” will have a materials library we could use for this, right?
Pavol, do you think this is possible?
Sheik